[SCTP]: Correctly set the length of sctp_assoc_change notification

sctp_assoc_change notification may contain the data from a received
ABORT chunk.  Set the length correctly to account for that.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c
index e27b11f..b43f1f1 100644
--- a/net/sctp/ulpevent.c
+++ b/net/sctp/ulpevent.c
@@ -206,7 +206,7 @@
 	 * This field is the total length of the notification data, including
 	 * the notification header.
 	 */
-	sac->sac_length = sizeof(struct sctp_assoc_change);
+	sac->sac_length = skb->len;
 
 	/* Socket Extensions for SCTP
 	 * 5.3.1.1 SCTP_ASSOC_CHANGE